The present invention relates to a tool for disintegrating coke.
In oil refineries, the last, otherwise unusable fraction of the crude oil is transformed into coke. This transformation is performed by feeding this fraction into drums which are filled with coke as the operation proceeds. Once the maximum filling level of the drums has been reached, the coke is cut out from the drums.
This so-called “de-coking” is usually carried out using high-pressure water jets which disintegrate the coke and wash it out of the drums. The tool for generating these high-pressure water jets is inserted into the drums from the top using a drilling rig. The de-coking is carried out in two stages. First, an opening in the drum is cut from the top to the bottom, then the tool is raised back to the top of the drum, and the coke is then disintegrated by the high-pressure water jets generated by cutting nozzles at about right angles to the axis of the bore.
The tool is adapted to assume two operating states, one for drilling an opening needed for moving the tool and then letting the disintegrated coke exit, and one for cutting the coke across the cross-section of the drum. The drilling nozzles accordingly send high-pressure water jets essentially parallel, or at an oblique angle, to an axis formed by the drill stem and the opening arising from the drilling. The cutting nozzles, on the other hand, generate high-pressure water jets aligned essentially at right or obtuse angles to the axis formed by the drill stem and the opening in the drum.
The switch-over between the operating states of drilling and cutting has to be quick and simple. The nozzles used in the tool are subject to wear and tear due to the high water pressure and thus have to be replaced frequently. Therefore, the tool must be adapted in such a way that the replacement of the nozzles can be carried out in a quick and safe manner.